[hotfix] [kafka tests] Build a flink-connector-kafka-0.9 test-jar

Build a test-jar including KafkaTestEnvironmentImpl so that Flink users can write end to end integration tests of their Flink jobs.

This closes apache#1972

flink-streaming-connectors/flink-connector-kafka-0.9/pom.xml

@@ -113,6 +113,39 @@ under the License.
 
  <build>
  <plugins>
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-jar-plugin</artifactId>
+ <executions>
+ <execution>
+ <goals>
+ <goal>test-jar</goal>
+ </goals>
+ <configuration>
+ <includes>
+ <include>**/KafkaTestEnvironmentImpl*</include>
+ </includes>
+ </configuration>
+ </execution>
+ </executions>
+ </plugin>
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-source-plugin</artifactId>
+ <executions>
+ <execution>
+ <id>attach-test-sources</id>
+ <goals>
+ <goal>test-jar-no-fork</goal>
+ </goals>
+ <configuration>
+ <includes>
+ <include>**/KafkaTestEnvironmentImpl*</include>
+ </includes>
+ </configuration>
+ </execution>
+ </executions>
+ </plugin>
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>